Fluorescence spectra hydrogen-bonding solvents

II). From this it must be concluded that the long-wavelength absorption of curve I is due to the intra-molecular hydrogen bond of TIN in unpolar solvents as the intensity of this band is reduced in polar solvents (curve II) and disappears completely in the spectrum of MT (without intramolecular hydrogen bond), curve III. Curve IVa represents the fluorescence and IVb the phosphorescence emission of both TIN and MT in... 

The concept of polarity covers all types of solute-solvent interactions (including hydrogen bonding). Therefore, polarity cannot be characterized by a single parameter. Erroneous interpretation may arise from misunderstandings of basic phenomena. For example, a polarity-dependent probe does not unequivocally indicate a hydrophobic environment whenever a blue-shift of the fluorescence spectrum is observed. It should be emphasized again that solvent (or microenvironment) relaxation should be completed during the lifetime of the excited state for a correct interpretation of the shift in the fluorescence spectrum in terms of polarity. 

Some 2-(2 -hydroxyaryl)benzotriazoles are UV stabilizers and they have received much attention as a result of their UV and fluorescence properties see review intermolecular hydrogen bonding. In contrast, the absorption spectrum of (65b) is relatively insensitive to solvents <81AJC69l). The absorption and fluorescence characteristics of 2-(2 -hydroxy-... 

Fluorescence spectroscopy was used also as a detection tool in case of a peptide based [2]rotaxane [72]. It was observed that in polar solvents like dimethyl sulfoxide (DMSO) fluorescence emission spectra were virtually same like those of the thread alone. Since fluorescence origins in this rotaxane from anthracene group, it was concluded that hydrogen bonds linking the macrocycle to the anthracene-based stopper were broken and the macrocycle resided on the alkyl side of the thread. When the solvent was hardly polar like 1,4-dioxane, the macrocycle rest bonded to the anthracene stopper and the spectrum broadened and red-shifted. By mean of time-resolved fluorescence spectroscopy, the authors demonstrated that it was... 

Weller observed the dual emission in the fluorescence spectrum of SA and MSA in methylcyclohexane (lO" mol/L), characterized by a strong emission with a maximum at 450 nm and a shoulder at 350 to 370 nm. The features of the emission spectrum of salicylic acid and its derivatives in solution are sensitive to the concentration of the solute and the solvent composition. This effect could be due to self-dimerization " or the existence of intermolecular hydrogen bonds formed by the carboxyhc add influencing the intramolecular hydrogen bond, C=0 -H0 in salicylic acid providing ESIPT. 

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